Why do not the medicine from the eye dropper flow out?

The medicine from an eye dropper does not flow out until pressure is applied to the bulb or the body of the dropper. This design creates a vacuum that holds the liquid inside when not in use. Additionally, the narrow opening of the dropper controls the flow, allowing for precise dispensing when needed. When the bulb is released, air pressure causes the liquid to be drawn back into the dropper, preventing spillage.